How to Calculate Concrete Volume for Your Project

Ordering the wrong volume of ready-mix concrete is one of the most expensive mistakes on any building site. Order too little and you get a cold joint where the second truck's concrete meets the first; order too much and you pay for concrete you tip away. The maths, thankfully, is simple — and we built a free concrete volume calculator that does it for you.

The Basic Formula

Concrete volume is length × width × thickness, with every dimension in metres:

Volume (m³) = Length (m) × Width (m) × Thickness (m)

Thickness is usually specified in millimetres, so divide by 1,000 first. A 100 mm slab is 0.1 m.

Worked Example: House Floor Slab

A slab of 10 m × 8 m at 100 mm thick:

10 × 8 × 0.1 = 8.0 m³. Add the standard 10% allowance for spillage, over-excavation and uneven ground: order 8.8–9 m³.

Round Columns

For circular columns use π × (diameter ÷ 2)² × height. A 230 mm column 2.7 m high: π × 0.115² × 2.7 ≈ 0.112 m³ per column. Ten columns ≈ 1.12 m³ — a single small load.

Strip Footings

Footings are calculated per metre run: width × depth × total length. A 600 mm wide, 200 mm deep footing around a 40 m perimeter: 0.6 × 0.2 × 40 = 4.8 m³.

Always Add the 10% Allowance

Site conditions are never perfect — slight over-dig, spillage during placing, pump priming losses. The industry standard is to order 5–10% above the calculated volume. Under-ordering by half a cube costs a short-load fee and risks a cold joint; over-ordering by half a cube costs a fraction of that.

What Strength Do I Need?

Volume is only half the order — the other half is the MPa grade. Our concrete strength grades guide explains which strength suits foundations, slabs and driveways, and our calculator recommends a grade per application. When in doubt, ask our sales team — telling us what you're pouring is usually enough for us to advise the right mix.

Technical review pending — this article is awaiting sign-off by Quick-Mix technical staff before deployment.

Request a Quote or Ask Our Team